Photosynthesis
Objective 1
• To trace the primary food source in a
food chain to the green plant
The Primary Food Source
• Green plants always found at the
beginning of the food chain.
• Why?
• The only organisms that can produce
their own food
• They are called producers
Objective 2
• To define photosynthesis
PHOTOSYNTHESIS
•Photo = light
•Synthesis = building up
DEFINITION
Pho to s ynthe s is
Process by which plants use wate r &
c arbo n dio xide to make
c arbo hydrate s in the presence of
lig ht and c hlo ro phyll.
Oxyg e n is given off during the
process.
Objective 3
• To understand the conditions necessary
for plants to make their own food
INTRODUCTION
What are the similarities
betweenYummy!!!
baking a cake and
photosynthesis?
REQUIREMENTS
•Rawmaterials
–Carbon dioxide
–Water
•Conditions
–Chlorophyll
–Light energy
Answers
•
Review 1
1. An organism that make its own food, e.g. green
plant
2. They make their own food by photosynthesis
•
Review 2
1. Textbook pg 19
•
Review 3
–
–
–
Raw materials: water & carbon dioxide
Conditions: sunlight & chlorophyll
End products: oxygen & glucose
Objective 4
• To outline the process of
photosynthesis by which plants
manufacture carbohydrates using raw
materials
• To state that food is stored as starch in
the plant
CARBON DIOXIDE
•From air
•Enters leaf by diffusion
•Pores: Stomata/Stoma
•Found underside of the leaf
Carbon
dioxide
WATER
•From soil
•Absorb by root hair
•Enter by osmosis
•Transport by xylem vessel
To Xylem
Vessel
Soil
Water
Root Hair
Water
Water
Water
CHLOROPHYLL
•Structure: Chloroplast
•Green pigment: Chlorophyll
•Absorb light energy
Plant Cell
Chloroplast
Leaf
LIGHT ENERGY
• Chlorophyll absorbs light energy from
sun
• Light energy converted into chemical
energy
• Chemical energy is needed to convert
carbon dioxide to carbohydrate
• Series of chemical reactions
CO2
H2O
H2O
Xylem
H2O
CO2
Surroundings
O2
O2
Light
Carbon Dioxide +Water
Chlorophyll
Glucose
STARCH+ Oxygen
WORD EQUATION
CARBON DIOXIDE + WATER
LIGHT ENERGY GLUCOSE + OXYGEN
CHLOROPHYLL
Review 4
1.
2.
3.
4.
5.
6.
7.
8.
Water, carbon dioxide, sunlight
Chlorophyll
It absorb the sunlight/light energy
Chloroplasts
The root hair absorb the water by osmosis
Xylem vessel
It enters through the stomata by diffusion
Carbon dioxide + water Light energy
glucose +
Chlorophyll
oxygen
Objective 5
• To state the conditions that affect the
rate of photosynthesis
LIMITING FACTORS
• Rate of photosynthesis is affected by:
–carbon dioxide,
–light intensity and
–temperature
LIGHT INTENSITY
• Higher light intensity, faster the rate of
photosynthesis
• After awhile, the rate will remain constant
• Due to limiting factors such carbon
dioxide concentration or temperature
CARBON DIOXIDE
• Carbon dioxide in the air is 0.03%
• Increasing the carbon dioxide
concentration to 0.1% increases the rate
of photosynthesis
• After awhile the rate will remain constant
due to limiting factor such as temperature
and light intensity
TEMPERATURE
• Temperatures below40°C, as it rises, the
rate of photosynthesis is faster
• At 40°C, photosynthesis begins to
decrease
• As temperature rises above 40°C,
photosynthesis stop as the enzymes
denatured
Other important things that plant
need to grow
• Minerals
– Found in soil and fertilizers
– Magnesium: chlorophyll formation
– Nitrogen: for making proteins
Objective 6
• To compare the conditions for healthy
growth of ornamental plants and large
scale crop productions
Ornamental Plants
• Use for decoration
• Usually grown in greenhouses
Ornamental Plants
• Conditions needed
– Types of soil – sand, organic matter
– Minerals – artificial or natural fertilizers
– Humidity - humid conditions better, by
spraying and misting
– Temperature - warm
– Light - bright
– Carbon dioxide – burning fuels
– Water – watering plants
– Pests – hand pick/pesticides
Large scale crops
• Includes rice, wheat, vegetables
• Relies on farming methods and
agricultural technology
• Plant in open field
Large scale crops
• Light, humidity, temperature and water
– cannot be controlled
• Fertilizers – mostly used artificial
fertilizers, machines
• Pests – planes to spray pesticides over
farm areas
Experiment
Question
Experiment: Testing for starch in
green leaves
• What does hot water do to the leaf?
– Kills the leaf to stop photosynthesis
• What does the alcohol do to the leaf?
– Breaks down chlorophyll – take the green colour
out of the leaf
• What is the original colour of iodine?
– brown
• What does it mean when iodine turn blueblack?
– Starch is present